High Speed Milling Of Titanium Alloy Research Articles

Formation Mechanism and Morphology Observation of Chips in High-Speed Milling of Titanium Alloy

The study of chip morphology during high-speed milling is crucial in determining processing quality, but the relationship between chip formation mechanisms and process parameters in titanium alloy high-speed machining has been a difficult issue. This paper investigates milling force and temperature variation, as well as chip morphology and surface quality after milling to improve workpiece surface quality and machining efficiency and provide guidance on selecting milling parameters. Factorial analysis confirms that milling speed worsens the serrated layer of chips. In addition, the experiment confirms the influence of tool rake angle on shear strain in the milling zone, the impact of rotational speed on tool wear, and the effect of tool wear on chip morphology. The results show that increasing milling speed worsens chip serration and increases tool wear.

Thermo-mechanical coupling behaviour when milling titanium alloy with micro-textured ball-end cutters

The high-speed milling of titanium alloy is a very complex nonlinear dynamic cutting process, and there are mutual coupling effects between multiple physical fields of the tool. Therefore, the thermo-mechanical coupling behavior of micro-textured ball-end milling cutters during the cutting of titanium alloy was studied in depth, combined with theoretical calculations, milling experiments and simulation analysis. First, based on the experimental data of milling titanium alloy, the stress field of the micro-textured ball-end milling cutter was solved. Then, the dimensional method was used to solve the temperature field of the micro-textured ball-end milling cutter. Finally, the thermo-mechanical coupling simulation analysis of the micro-textured ball-end milling cutter was carried out, and the stress concentration area and tool breakage area of the micro-textured ball-end milling cutter under the thermo-mechanical coupling effect are obtained. This in turn gives a theoretical basis for further improving the performance and tool life of micro-textured cutters.

Optimization of process parameters in the high-speed milling of titanium alloy TB17 for surface integrity by the Taguchi-Grey relational analysis method

TB17 is an ultra-high-strength titanium alloy, a material typically difficult to machine. The surface quality and integrity of titanium alloy TB17 are poor after machining, which can seriously affect its service performance and restrict its fields of application. Therefore, the optimization of high-speed milling process parameters for the new ultra-high-strength titanium alloy TB17 was investigated based on multiple performance characteristics, including surface roughness, surface microhardness, and surface residual stress. The Taguchi method with grey relational analysis was utilized for the experiments. Additionally, analysis of variance was employed to evaluate the most influential factors for surface integrity in the high-speed milling of titanium alloy TB17. The results of the analysis using the Taguchi-Grey relational analysis method indicate that the preferred combination of high-speed milling process parameters are as follows: the cutting fluid condition of H-1 fine grinding fluid, using a milling speed of 100 m/min, a feed per tooth of 0.02 mm/z, an axial depth of cut of 1 mm, a radial depth of cut of l.5 mm, a rake angle of 18°, a clearance angle of 12°, and a helix angle of 60°. Moreover, the analysis of variance reveals that milling speed has the greatest effect on the surface integrity in the high-speed milling of the TB17 titanium alloy, and the contribution percentages for each factor are as follows: the cutting fluid condition (3.98%), milling speed (25.89%), feed per tooth (8.96%), axial depth of cut (1.29%), radial depth of cut (13.71%), rake angle (17.17%), clearance angle (6.62%), and helix angle (15.64%).

Chip Formation in High-Speed Milling of Titanium Alloy with PCD Tools

This paper presents a detailed analysis of chip morphology through an experimental study of high-speed milling of Ti-6Al-4V alloy with PCD tools. Milling tests were conducted for cutting speed range from 125 m/min to 2000 m/min with water-soluble cutting fluid. The collected chips were firstly examined with a digital cameras and the free surface of the chips was analyzed by a scanning electron microscope (SEM). Geographical parameters of chip morphologies were described in saw-tooth/lamella frequency on the free surface and chip width. Experimental results show that the variation of chips in high-speed end milling of Ti-6Al-4V alloy is as follows, long and straight-shaped → spiral-shaped → curly-shaped → irregular-shaped. The free surface of chips exhibits saw-tooth lamella structures. The lamella becomes clearer and more obvious at higher cutting speeds. Within the same measurement distance, there is a sharp decrease in the lamella number within same measuring range. This should be attributed to the enhancement of the thermal mechanical coupled field applied to the chip formation processes.

Spindle Speed Selection for High-Speed Milling of Titanium Alloy Curved Surface

The development of high-speed milling technology provides an effective processing method for titanium alloy curved surface with high quality, and the spindle speed is an important machining parameter for the high-speed milling of titanium alloy curved surface. The variation of the geometric features of the titanium alloy curved surface results in the sharp fluctuation of the cutting force as well as the vibration of machine tool, which not only makes a severe impact on the surface machining quality and the tool life but also greatly affects the efficiency of the high-speed milling. An experimental study is carried out to determine the spindle speed for high-speed milling of the titanium alloy curved surface based on the cutting force. The experimental results indicate that in high-speed milling process, the cutting force is associated with the geometric feature of the curved surface and the change of cutting force is relatively smooth when the spindle speed is in the range from 9000 to 13,000 rpm for the machining of titanium alloy curved surface.

An empirical study on the characterization of machined surface integrity by chip morphology in dry end-milling of titanium alloy

Titanium alloys manifest low thermal conductivity and high work hardenability in machining. These alloys are thus considered as difficult-to-machine at higher cutting speeds and pose serious problems in machining such as degraded machined surface and rapid tool-wear. Mostly, the integrity of the machined surface is assessed by post-process microscopic examination or by metallurgical testing techniques where machined workpiece needs to be further processed to perform subsequent testing on sophisticated equipment in usually meticulous ways. This study presents a qualitative but simple approach for the rapid characterization of the machined surface integrity in high-speed milling of titanium alloy. It has been established empirically that the chip morphology carries significant information about the machined surface integrity, and hence, can be considered as a reliable representative of the machined surface integrity.

Simulation for Cutting Force and Temperature in High-Speed Milling of TB6 Titanium Alloy

High-speed milling of titanium alloys is widely used in aviation and aerospace industries for its high efficiency and good quality. In order to optimize machining parameters in high-speed milling TB6 titanium alloy, temperature distribution on the workpiece and the tool are analyzed, and the effect of milling parameters on milling force and milling temperature are investigated. The results show that the highest temperature appears on rake face, and near to the tool tip. With increasing of cutting time, heat affected zone on tool is bigger than that on workpiece. Milling temperature is most sensitive to the variation of milling speed, next sensitive to the variation of feed per tooth, and it is least sensitive to milling depth. Milling force is most sensitive to the variation of milling depth, next sensitive to the variation of feed per tooth, and it is least sensitive to milling speed.

Experimental Study on Surface Integrity in High-Speed End Milling of Titanium Alloy TB6

High-speed milling of titanium alloy is widely used in aviation and aerospace industries for its high efficiency and good quality. In order to obtain good surface integrity, experiments of high-speed end milling were performed to investigate the influence of milling parameters on surface integrity. The results show that the surface roughness, surface topography, residual stresses and microhardness are significantly affected by feed per tooth and milling speed. Good surface state was obtained when feed per tooth, milling speed, milling width and milling depth is close to 0.08mm/z, 100m/min, 7mm, and 0.2mm respectively. High-speed milling is favourable for improving machining efficiency and surface quality and therefore should be widely used in manufacturing of aircraft thin-wall structure parts. This study provides a theoretical basis and experimental evidence for the surface integrity of machined high-strength alloy.

Influence of high-speed milling parameter on 3D surface topography and fatigue behavior of TB6 titanium alloy

High-speed milling of titanium alloys is widely used in aviation and aerospace industries for its high efficiency and good quality. In order to optimize the machining parameters in high-speed milling TB6 titanium alloy, experiments of high-speed milling and fatigue were conducted to investigate the effect of parameters on 3D surface topography and fatigue life. Based on the fatigue fracture, the effect mechanism of surface topography on the fatigue crack initiation was proposed. The experiment results show that when the milling speed ranged from 100 m/min to 140 m/min, and the feed per tooth ranged from 0.02 mm/z to 0.06 mm/z, the obtained surface roughness were within the limit (<0.8 μm). Fatigue life decreased sharply with the increase of surface equivalent stress concentration factor. The average error of fatigue life between the established model and the experimental results was 6.25%. The fatigue cracks nucleated at the intersection edge of machined surface.

Investigation Into the Effect of Cryogenic Minimum Quantity Lubrication in High-Speed Milling of Titanium Alloys

Investigation Into the Effect of Cryogenic Minimum Quantity Lubrication in High-Speed Milling of Titanium Alloys

Microstructural damage during high-speed milling of titanium alloys

The majority of aero-structural titanium alloys are high-speed milled. This paper identifies microstructural subsurface damage in the form of intense slip bands after high-speed milling of Ti–6Al–4V and Ti-834. Such microstructural features are undetected by current surface integrity techniques. The alignment and density of the intense slip bands were found to be dependent on the subsurface alpha grain orientation. Such microstructural subsurface damage could degrade in-service properties, due to a reduction in fatigue crack initiation resistance.

The Application of Cryogenic Pneumatic Mist Jet Impinging in High-Speed Milling of Ti-6Al-4V

To solve the problems caused by high temperature in the cutting zone during high-speed milling of Titanium alloys, some cooling methods are employed, such as cold air cooling, high pressure coolant jet impinging, MQL, etc. But all have their shortfalls, both in cooling efficiency and environmental pollution. Here a new high efficiency cooling technology-cryogenic pneumatic mist jet impinging (CPMJI) cooling technology is offered. In this technology, a little quantity of coolant is carried by high pressure cryogenic air (-20) and reaches the machining zone in the form of mist jet. This paper mainly focuses on the cooling effects of CPMJI in high-speed milling of Titanium alloy Ti-6Al-4V, as compared with dry, cold air cooling and MQL conditions. CPMJI greatly reduced the temperature in cutting zone and flank wear of tool.

A Hybrid Cutting Force Model for High-speed Milling of Titanium Alloys

In this paper, the Johnson-Cook (JC) strength model is used to describe the flow stress of Ti6AI4V and to estimate two important parameters in Oxley's model: the strain-rate constant and the angle made by the resultant force and the shear plane. The JC model is also incorporated into a finite element method (FEM) simulation for the deformation process of T16AI4V. Finally, a hybrid cutting force model based on the FEM simulation and Oxley's theory is proposed to predict cutting forces when machining Ti6AI4V. Experimental results are found to substantiate the developed model.

Tool wear characteristics of binderless CBN tools used in high-speed milling of titanium alloys

Titanium alloys are difficult-to-cut materials, and the performance of conventional tools is poor when used to machine them. In this paper, a new tool material, which is binderless cubic boron nitride (BCBN), is used for high-speed milling of a widely used titanium alloy Ti–6Al–4V. The performance and the wear mechanism of the tool have been investigated when slot milling this alloy. This type of tool manifests longer tool life at high cutting speeds. Analyses based on the SEM and EDX suggest that adhesion of workpiece, attrition and diffusion–dissolution are the main wear mechanisms of the BCBN tool when used in high-speed milling of Ti–6Al–4V.

High-speed milling of titanium alloys using binderless CBN tools

The performance of conventional tools is poor when used to machine titanium alloys. In this paper, a new tool material, which is binderless cubic boron nitride (BCBN), is used for high-speed milling of a widely used titanium alloy Ti–6Al–4V. The performance and the wear mechanism of the BCBN tool have been investigated when slot milling the titanium alloy in terms of cutting forces, tool life and wear mechanism. This type of tool manifests longer tool life at high cutting speeds. Observations based on the SEM and EDX suggest that adhesion of workpiece and attrition are the main wear mechanisms of the BCBN tool when used in high-speed milling of Ti–6Al–4V.